1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a storage medium storing a program that measure a shape to be picked up, and more particularly to an image processing apparatus, an image processing method, and a storage medium storing a program that perform image pickup of characters, patterns, and the like written onto paper or the like with a pen, perform geometric transformation for picked-up images, and perform natural input character analysis and reading processing.
2. Description of the Related Art
With the development of a computer, various input devices such as a keyboard, mouse, and tablet are being developed. As devices for inputting handwritten characters, a tablet as shown in FIG. 31 is finding widespread use.
A tablet-type input device as shown in FIG. 31 requires dedicated input devices. Since a so-called dedicated pen 3102 and a dedicated input device 3101 are used, the operation environment is different from the input environment of writing to paper. To input characters written to normal paper to a personal computer or the like, they must be inputted to a scanner, digital camera, or the like.
In Japanese Published Unexamined Patent Application No. Hei 4-126447, there is disclosed a system which obtains images comparable to the resolution of flatbed-type scanners employing one-dimensional line sensors, using a two-dimensional image pickup element. To be more specific, a distance input part is used in the two-dimensional image pickup element to calculate the shape of subjects, and manuscript information is reproduced on a flat plane by geometric transformation.
Furthermore, in Japanese Published Unexamined Patent Application No. Hei 11-136563, there is disclosed a system which reads an image by detecting manuscript tilt information by: a distance measuring sensor, which includes an imaging optical system having an automatic focus mechanism, and an image pickup element for reading a manuscript image through the imaging optical system, and measures a distance from an image pickup face of the manuscript image to the center of the image pickup element (optical axis); a manuscript face angle input part that inputs information on an angle of a face on which a manuscript image is placed, with respect to a horizontal face; and range information of the distance measuring sensor and angle information of the manuscript face angle input part.
In Japanese Published Unexamined Patent Application No. Hei 11-136564, there is a system which uses a distance measuring part, which includes an imaging optical system, and an image pickup element for reading a manuscript image through the imaging optical system, and measures respective distances from any three points on an image pickup face of the manuscript image to the image pickup element, and range information of the three points obtained by the distance measuring part, to detect information on a tilt of the manuscript face to the image pickup element so that highly precise images can be obtained by keeping track of tilts of the manuscript face to the image pickup element face.
General methods for measuring distances and shapes include a space coding method as disclosed in Japanese Published Unexamined Patent Application No. Hei 5-332737, and a stereo image method having plural image pickup elements.
To input or recognize handwritten characters, a tablet device having a dedicated pen and a dedicated input device as described above is used, or after an image is read by keeping track of manuscript tilts using the above-described distance measuring part, the image is analyzed by geometric transformation (projective transformation). However, the above-described configuration has the disadvantage that the apparatus becomes costly because a special distance measuring part is required, bringing the apparatus into a large scale.